AB0118 PORPHYROMONAS GINGIVALIS AMOUNT IN THE TONGUE BIOFILM IS ASSOCIATED WITH EROSIVE ARTHRITIS IN SYSTEMIC LUPUS ERYTHEMATOSUS
Authors: F. Ceccarelli, M. Saccucci, F. Natalucci, G. Olivieri, E. Bruni, R. Iacono, T. Colasanti, G. Di Carlo, C. Alessandri, D. Uccelletti, P. Russo, A. Pilloni, F. Conti, A. Polimeni
Journal: Annals of the Rheumatic Diseases (2022)

Background Several data have demonstrated the occurrence of erosive arthritis in Systemic Lupus Erythematosus (SLE) patients. However, few studies have focused on the pathogenic mechanisms involved in this feature. The implication of oral pathogens has been proved in Rheumatoid Arthritis: in particular, Porphyromonas gingivalis (Pg), by inducing citrullination, could trigger autoimmune response. Objectives We evaluated amount of Pg of the tongue in a cohort of SLE patients with arthritis, focusing on the association with the erosive phenotype. Methods SLE patients with arthritis were enrolled. We evaluated the presence of ACPA and RF by using commercially enzyme-linked immunosorbent assay kits. SLEDAI-2k was applied to assess disease activity and DAS28 to assess joint inflammatory status. Erosive damage was evaluated by ultrasound at level of metacarpophalangeal and proximal interphalangeals joints. All subjects underwent a tongue cytologic swab in order to quantify the amount of Pg (real-time PCR). The bacterium expression was obtained from the ratio between the patient’s DNA amount and that obtained from healthy subjects. Results The present analysis included 33 SLE patients (M/F 3/30; median age 47 years, IQR 17; median disease duration 216 months, IQR 180). Concerning activity at the time of the enrollment, we found a median DAS28 value of 3.8 (IQR 2.8) and a median SLEDAI-2k of 4 (IQR 5). Twelve patients (36.4%) showed US-detected erosive damage in at least one joint, significantly associated with ACPA positivity (p&lt;0.0001). Furthermore, patients with erosive damage showed significantly higher median DAS28 values in comparison with those without [4 (IQR 3.1) versus 3.2 (IQR 2.1), p=0.03]. Moving on the oral pathogen analysis, we found a mean Pg ratio of 19.7±31.1 (median 6.6, IQR 22.3). When dividing patients according to the presence of erosive damage, we found higher Pg amount in SLE patients with this phenotype in comparison with those without (31.4±44.3 versus 12.9±19.2, p=ns; Figure 1A). Thus, we used Pg mean values as threshold, identifying two groups of patients, namely highPg and lowPg. In a receiver operating characteristic curve analysis (ROC), this threshold resulted in the most sensitive and specific one (sensitivity of 85%; specificity of 50%). As reported in Figure 1B, erosive damage was significantly more frequent in highPg patients in comparison with lowPg (60.0% versus 26.0%, p=0.001). Furthermore, highPg patients showed higher prevalence of skin manifestations, serositis and neurological involvement compared to lowPg patients (p=0.005, p=0.03, p=0.0001, respectively). Conclusion The possible contribution of oral microbiota in SLE erosive arthritis was here evaluated for the first time, finding a significant association between erosive damage and higher expression of Pg at tongue level. Disclosure of Interests None declared